Modern electronic equipment such as televisions, telephones, radios and computers are often constructed of solid state components. Solid state components have no moving parts, but operate based on the movement of charged carriers. As a result, solid state components are extremely reliable, very small and relatively inexpensive.
Solid state components may be transistors, capacitors, resistors and the like based on or utilizing semiconductor materials. Such components are typically formed on a wafer of substrate material as part of an integrated circuit. In the integrated circuit, the solid state components are suitably laid out, isolated and interconnected to form memory arrays and other types of useful circuits. The components are conventionally isolated by insulation layers formed between active areas, leads and other conductive regions and interconnected by conductors passed through the insulation layers to connect the active areas, leads and other conductive regions at specified locations.
To allow vertical interconnection of components in an integrated circuit, an active area, lead or conductive region is typically enlarged at a contact point to horizontally overlap a contact point of the connecting active area, lead or conductive region. This enlargement of contact points, however, increases the size of the integrated circuit and causes difficulty in laying out the integrated circuit. The enlargement is especially problematic for DRAM cells and other types of circuits that have an array of repeatedly duplicated components and wiring. In addition, the enlarged contact points increases parasitic capacitance of active areas, leads and conductive regions, which reduces the speed of the integrated circuit.
Alternatively, an intermediate wiring layer, or pad, has been used to interconnect active areas, leads or conductive regions of an integrated circuit. In this arrangement, the intermediate pad is typically disposed between and horizontally overlaps the contact points of active areas, leads or conductive regions to be interconnected. A first vertical conductor connects a first active area, lead or conductive region to a first side of the intermediate pad and a second vertical conductor connects a second active area, lead or conductive region to a second side of the intermediate pad. The intermediate pad, however, requires additional material and process steps to fabricate, including relatively expensive photo lithography masking steps.